Research On 2D/3D Bulk Heterojunction Perovskite Solar Cells Based On ?R-NH₃?₂?MA?_n-1Pb_nI_3n+1

Organic-inorganic hybrid perovskite solar cells have attracted much attention in the field of photovoltaics due to their high absorption coefficient,long carrier diffusion distance,high carrier mobility,suitable bandgap and solution-processability.At present,the efficiency of 3D-structured perovskite solar cells has reached 23.7%,while the practical application is limited by instability of 3D perovskite solar cells.Because of its excellent stability and tunable band gap,2D layered perovskite materials have attracted the attention of researchers.However,the efficiency of 2D perovskite solar cells is still far behind that of 3D perovskite solar cells.This paper combines the high efficiency of3D perovskite solar cells and the high stability of 2D perovskite solar cells,and carried out the following research work:1.Phenylethylamine?PEA:C₆H₅C₂H₄NH₂?and methylamine?MA:CH₃NH₂?was used as organic elements.Two-dimensional perovskite films of?PEA?₂?MA?_n Pb_nI_3n+1?n=1,2,3?were prepared by one-step spin-coating method.The perovskite films with n=3?PEA?₂?MA?₂Pb₃I₁₀ exhibited the best photovoltaic properties through characterization of structure,photoelectric properties and devices.Based on the 2D perovskite film with n=3,we annealed the film and studied the effect of annealing atmosphere on the properties of the film.The results show that after annealing in MAI atmosphere,3D Perovskite thin layer was formed in 2D perovskite,forming 2D/3D heterostructure perovskite thin film.After further annealing in DMF,the film recrystallization occurred and the crystallization performance was further improved.The annealed film was prepared into a solar cell device,and the energy conversion efficiency?PCE?of the device with the best performance reached 13.05%,and its V_OC=1.07 V,J_SC=17.93 mA/cm²,and FF=68%.The device has not been encapsulated in any way,after 500 hours of storage at 65%relative humidity,and it still has 75%of the original efficiency.The efficiency of the 2D perovskite solar cells was improved under the premise of ensuring stability.2.The use of benzylamine?PMA:C₆H₅CH₂NH₂?and MA as organic elements is intended to shorten the spacing of the inorganic layers,promote interlayer transport,and improve charge transport efficiency.2D?PMA?₂?MA?_n-1Pb_n I_3n+1?n=1,2,3?perovskite thin films were prepared by one-step spin-coating method.Their structure,optical properties and device properties were studied.The results show that the?PMA?₂?MA?₂Pb₃I₁₀ thin films with n=3 have the best photovoltaic properties.Therefore,the film of n=3 was used as the main body to study the effect of annealing time and annealing atmosphere on the properties of the film by atmosphere annealing.The results show that after annealing in MAI atmosphere,a 3D perovskite thin layer was formed in the 2D perovskite thin film,and a 2D/3D bulk heterojunction perovskite was formed.With the prolongation of annealing time,the proportion of 3D perovskite can be controlled.After annealing in DMF atmosphere,the crystallinity of the film was improved.The PCE of the solar cell with the best performance was 9.17%,V_OC=0.926V,J_SC=18.16 mA/cm²,FF=54.4%.3.Using a shorter chain of butylamine?BA:CH₃CH₂CH₂CH₂NH₂?and MA as organic elements,?BA?₂?MA?_n-1Pb_nI_3n+1 2D perovskite thin films were prepared by one-step spin-coating method.Characterization of structure and properties by experiments,it is considered that the n=3?BA?₂?MA?₂Pb₃I₁₀ film has excellent photoelectric properties.On the n=3 perovskite film,a 2D/3D bulk heterojunction perovskite film was prepared by annealing in a MAI atmosphere,and the proportion of the 3D perovskite component was controlled by the reaction time.Then,the film was crystallized by DMF atmosphere annealing,and prepared into a solar cell device,and finally the device PCE reached 7.96%,wherein V_OC=0.8991 V,J_SC=17.93 mA/cm²,and FF=47.7%.